During the worst campus shooting spree in American history,Virginia Tech officials locked down some administrativebuildings and told their own families more than an hour and ahalf before the rest of the campus was alerted, according torevisions made in the state's official report on the tragedy.

Trying to minimize the false alarm factor I would guess. Then again, if it looks real enough to tell your own family, you should pass the news on. The other variables to consider would be "risk factor" I have noticed that this is highly variable. You of all people know this!